Eastern rockhopper penguin
| Eastern rockhopper penguin | |
|---|---|
| |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Sphenisciformes |
| Family: | Spheniscidae |
| Genus: | Eudyptes |
| Species: | |
| Subspecies: | E. c. filholi
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| Trinomial name | |
| Eudyptes chrysocome filholi Hutton, 1878
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| Synonyms | |
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Eudyptes filholi | |
The eastern rockhopper penguin (Eudyptes chrysocome filholi), also known as the tawaki piki toka, is a crested penguin with yellow crest feathers.[1] It is a subspecies of the southern rockhopper penguin (Eudyptes chrysocome) found in subantarctic regions and the Indian Ocean.[1] It is one of the smallest crested penguins and has distinctive pink margins around its bill.[2]
Description
The eastern rockhopper penguin is a small, crested penguin with a black back and throat, a white belly and pink feet.[1] This seabird measures approximately 45–55 cm in length, and weighs 2.2–4.3 kg.[3] It has a thin yellow stripe that stretches from its lower forehead, over its red eye and splits into crest feathers at the back of its head.[2] The crest feathers are composed of long, thin, spiky yellow feathers on either side of the penguin's head and they are joined by shorter black feathers.[2] Rockhopper penguins have an orange-brown bill and the eastern rockhopper penguin has distinctive pink margins around the bill.[1] Males and females differ in body size and size of their bill;[1] males are generally larger and have a thicker bill.[2]
Fledglings, which are around 65 days old, are bluish black all over and lack crest feathers.[1] They also have a smaller, thinner bill than juveniles and adults.[1] Juveniles, which are penguins aged 1 to 2 years old, are a black-brown color with a grey throat.[1] They develop a brown-orange bill that is darker than the adult coloring and have small yellow crest feathers.[1] Eastern rockhopper penguins molt and get their adult plumage at 2 years old.[1]
Taxonomy
The rockhopper penguin can be divided into two species; the northern rockhopper penguin (Eudyptes moseleyiI) and the southern rockhopper penguin.[2] These populations differ in many ways including morphological, ecological and behavioural differences.[2] The northern rockhopper penguin is larger than its southern counterpart and has longer crest feathers.[4] Other morphological differences include different color patterns on the underside of their flipper and different size eyestripes.[4] They also exhibit different behavioural traits such as foraging in different water temperatures.[2] Two subspecies of the southern rockhopper penguin are recognized; the eastern and the western rockhopper penguin (Eudyptes chrysocome chrysocome).[2] These subspecies differ mainly in their distribution; the western species is found in Cape Horn, South America and the Falkland Islands while its eastern counterpart occupies the Southern Indian and Pacific Ocean.[2] The eastern rockhopper penguin can also be distinguished by its pink margins around the bill.[2]
Habitat and Distribution
The eastern rockhopper penguin is found in the southern Indian and Pacific ocean from Prince Edward Islands to the Antipodes Islands.[2] Rockhopper penguins, in general, occupied a circumpolar distribution in the arctic during breeding season.[1] Eastern rockhopper penguins breed in the Marion Islands, Macquarie island and subantarctic islands in New Zealand such as the Antipodes islands and Campbell island.[4] These penguins occupy a mainly marine pelagic habitat and only return to land to breed and moult.[1] They spend the winter months, approximately April to October, in the southern Indian Ocean foraging for food and can spend up to 6 months at sea.[1] They travel, on average, 2000 to 4000 km away from their breeding site during this winter period.[1] This species mainly forages in cool waters; ocean temperatures of less than 4.5 degrees Celsius.[5]
Eastern rockhopper penguins are surface nesters and will build their nest on slopes or rocky shores near the coastline.[2] Colonies will usually form on steep cliffs near the sea and can contain tens-of-thousands of nests.[1] Their nests are made of small pebbles and can occasionally contain some vegetation.[1] Some colonies have settled within grasslands such as tussock, however the soil often erodes down to rock with the accumulation of guano and trampling over a few decades.[1] Eastern rockhopper penguins are rarely found more than 200 meters away from the coastline, since it is ideal to remain near their food supply.[1]
Behavior
Vocalization
Eastern rockhopper penguins use calls for parent-chick recognition when returning to the colony with food.[6] They also use a song for courtship that can be described as a short repeated rhythmic ascending song.[2][7] The song of an adult rockhopper penguin can have 5-30 syllables with the first syllable the longest.[6] Their contact call used by chicks and adults is a very short shrill bark.[2]
Diet and foraging
Eastern rockhopper penguins feed on a variety of fish, crustaceans and cephalopods such as krill and squid.[8] Their diet can differ depending on where they are in their life cycle.[5] During their pre-moult season, eastern rockhopper penguins mainly consume crustaceans, while during the breeding period their diet heavily relies on euphausiids in the Marion islands.[5] Different breeding location will also impact their diet; chicks in the Campbell island were found to mainly consume dwarf cod.[9] Rockhopper penguins highly depend on a predictable food source near their nesting habitat to feed their chicks.[10] However, if necessary rockhopper penguins can forage up to 120 km away from their breeding grounds to find food for their chicks.[8]
They are diurnal divers; the majority of their foraging activity occurs during the day with the deepest dives occurring at sunrise.[11] When searching for food, they usually stay at a depth of 6m and dive down 30-50m in the water column to catch their prey.[11] They tend to forage in cool waters since they are most productive.[5] They also selected foraging areas with large generation of eddies currents.[5] This type of current supports high aggregations of prey species.[5]
The predators of the rockhopper penguin includes fur seals and sea lions.[3] As well, brown skuas (Stercorarius antarcticus) and northern giant petrel (Macronectes halli) prey on rockhopper penguin eggs and chicks.[3]
Reproduction
Breeding season starts in October for eastern rockhopper penguins; males return to the breeding colony first and the females follow shortly after.[1] Courtship begins between pairs and both sexes fast until the female lays the first eggs usually around the beginning of November.[1] After the eggs are laid, the male and female will share all the parental duties.[1] The first incubation period is shared and both parents will fast during this time, approximately 7 days.[11] After this, the female takes the first solo incubation shift while the male goes to forage at sea, this can last up to 3 weeks.[11] Once the male returns, he takes over incubation while the female forages for approximately 10 days, by the time she returns, the chicks have hatched.[11] After the chicks hatch, the male will guard the chicks and continue to fast while the female forages and returns with food for the chicks.[3] The chicks form creches when they are around 24 days old and during this time both parents foraged and return with food.[1] A creche is a common occurrence in bird species when the juveniles form protective groups to allow the parents to forage.[12] Parent penguins continue to feed chicks until they fledge around February[13] when they are approximately 65 days old.[1] Adult penguins will return to the breeding colony in April to moult before their winter at sea.[3]
Threats and Conservation
The eastern rockhopper penguin is considered a vulnerable species due to rapid population declines.[13] This decrease in population is mostly seen in breeding regions since it is the easiest form of census.[3] Most research agrees that the decline in rockhopper penguins is due to low food availability and decrease in food quality driven by climate change.[1][3][13] Due to climate change, sea surface and ocean temperatures are changing and this effects the distribution of prey populations.[3] Rockhopper penguins, and many other species, are sensitive to changes in water temperature[13] and as a consequence, adult penguins must forage farther away from breeding colonies.[3] They often return with smaller amounts of food for their chicks which leads to a decrease in body mass.[3] Low food availability also has a large effect on penguin's moult period.[3] Moulting is a very energy demanding process and requires penguins have sufficient body mass.[3] Due to poor diet, there is an increase in mortality during the moulting season.[3] Low food quality and abundance in wintering regions have also led to an increase in adult mortality.[3] Climate change has additionally affected the amount and intensity of storms in breeding ranges.[13] Intensity of winds displace prey populations and reduce penguin foraging success.[13]
References
- ^ a b c d e f g h i j k l m n o p q r s t u v w x Morrison (2013). "Eastern rockhopper penguin | New Zealand Birds Online". New Zealand Birds Online: The digital Encyclopaedia of New Zealand Birds. Retrieved 3 October 2020.
- ^ a b c d e f g h i j k l m n Martínez, Isabel; Christie, David; Jutglar, Francesc; Garcia, Ernest; Kirwan, Guy M. (2020-03-04). "Southern Rockhopper Penguin (Eudyptes chrysocome)". Birds of the World.
- ^ S2CID 253809686.
- ^ S2CID 6087437.
- ^ S2CID 253737022.
- ^ ISSN 1600-048X.
- ^ Hutton, FW (1879). "Southern Rockhopper Penguin (Eudyptes chrysocome)". Xeno-canto. Retrieved 8 October 2020.
- ^ S2CID 253809589.
- ^ Sagar, PM; Murdoch, R; Sagar, MW; Street, A Yardley; Thompson, DR (2005). "Rockhopper penguin (Eudyptes chrysocome filholi) foraging at Antipodes Islands" (PDF). Notornis. 52: 75–80.
- ISSN 0171-8630.
- ^ ISSN 1480-3283.
- ^ "Creches". web.stanford.edu. Retrieved 20 October 2020.
- ^ a b c d e f "Southern Rockhopper Penguin (Eudyptes chrysocome) - BirdLife species factsheet". BirdLife International. 2020. Retrieved 7 October 2020.
Further reading
Morrison, K.W; Battley, P.F; Sagar, P.M (February 2015). "Population dynamics of Eastern Rockhopper Penguins on Campbell Island in relation to sea surface temperature 1942-2012: current warming hiatus pauses a long-term decline". Biodiversity Conservation. 38 (2): 163–177.
External links